It is well known that contactless charging systems use inductive charging to recharge portable devices without the need for electrically connecting one or more contact terminals for transferring electrical energy to the portable device. Examples of such portable devices include cordless telephones, electronic toothbrushes, and other electronic convenience devices. Such devices typically include a base charging unit and a portable device. The base charging unit includes a primary inductive coil electrically connected to a power source. The power source provides an alternating current (AC) voltage supply (or a direct current voltage supply rectified to produce an AC voltage supply) for energizing the primary inductive coil. The primary inductive coil generates an electromagnetic field for inducing an electrical charge on a secondary inductive coil within in the portable device. The secondary inductive coil may be located within a rechargeable battery housing or elsewhere in the portable device. The energy induced in the secondary inductive coil is then converted to a DC voltage supply for charging the rechargeable battery.
As is readily apparent to those skilled in the art, the transfer of inductive energy from the primary inductive coil to the secondary inductive coil is optimized when the primary and secondary inductive cells are aligned about a single axis of an electromagnetic field having various vectors of transmission/reception. As a result, efficiency of energy transfer for recharging of the remote device is dependent upon the orientation of the portable device to the base unit (i.e., the orientation of the vector components of the transmitting electromagnetic field of the primary inductive coil to the orientation of the vector components of the receiving electromagnetic field secondary inductive coil). To properly position the portable device for optimum charging the rechargeable battery, a docking port or cradle is provided that orients the remote device to the base charging unit. This aligns both the primary and the secondary inductive coils along respective axes so that the vector components of each inductive coil are aligned for transmission and reception. However, this requires that the remote device be fully seated in the same location of the charging port every time charging of the rechargeable battery is required. Any misalignment or improper docking of the remote device in the charging port may result in inadequate charging of the re-chargeable battery.
Other methods known for aligning the electromagnetic fields of the primary and secondary inductive coils include automatically rotating the primary inductive coil about an axis to align the vector components of transmitting primary inductive coil with the vector components of the secondary inductive coil. Such devices include a primary inductive coil that is rotatable about an axis via a motorized mechanism. A controller controls the rotation of the primary inductive coil as it is rotated about the axis. A shaft encoder/decoder is utilized to monitor the degree of rotation and provide signals to the controller. As the primary inductive coil is rotated about the axis, the secondary inductive coil of the rechargeable battery absorbs electrical energy induced by the primary inductive coil. The energy absorbed by the secondary inductive coil is measured by the controller. The controller determines the final position of the primary inductive coil based on the current measurement. As the vector components of the primary inductive coil and secondary inductive coil becomes increasingly aligned, the current measurement increases. Based on the peak transmission of electrical energy between the primary and secondary inductive coils at a respective degree of rotation, the controller will re-align the position of the primary inductive coil for optimum recharging performance. Although this automated process eliminates the operation of manually orienting the remote device to the base unit for optimum charging, additional cost and packaging space are required for the additional devices required to execute this automated process. Such additional devices include the controller, the mechanical mechanism for rotating the coil, current drivers, and the shaft encoder/decoder for monitoring rotational position of the coil.
In addition, because cellular telephones are shaped and sized dimensional different along with different battery orientations, docking ports are sized differently, particularly in a vehicle, for cradling a respective cellular telephone. What would be useful would be to have a charging apparatus that can accommodate various sized and shaped cellular telephones including the different battery orientations.